The semiconductor integrated circuit (IC) industry has experienced exponential growth and has progressed in pursuit of higher device density and performance as well as lower costs. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component that can be created using a fabrication process) has decreased. However, typical semiconductor devices face higher obstacles due to physical constraints. Accordingly, a wide variety of approaches of fabrication processes for scaling down of semiconductor device have been developed.
Among the semiconductor device, flash memory is an electronic non-volatile computer storage medium that can be electrically erased and reprogrammed. A typical flash memory includes a memory array having a large number of memory cells arranged as an array. It can be used in a wide variety of commercial and military electronic devices and equipment. Common types of flash memory cells include stacked gate memory cells and split gate memory cells. The aggressive scaling of the third generation embedded super-flash memory (ESF3) enables designing flash memories with very high memory array density, lower power consumption, higher injection efficiency, and less susceptibility to short channel effects, and over erase immunity.